The present invention is in the field of metalworking and pertains to cutting tools, particularly to an improved method and apparatus for shearing metal and other sheet materials used to manufacture parts and systems.
In the art of metalworking, a very common operation is the shearing of metal or some other sheet material as performed by a shear tool. Sheared products are typically used as components in other processes of fabrication. In some cases sheared components represent finished pieces that need no further manufacturing. Shearing operations are to some extent dangerous and, depending on the size of job and type of shear equipment, have certain rules that must be followed for maintaining safety during operation. For example, in current art hand shearing, a user grasping a conventional shear tool and attempting a shearing action on a work piece invariably has his or her hands at or near the material cutting plane of the work piece, thus interfering with the material being sheared. Usually heavy gloves are required to protect against newly sheared material edges, as well as safety glasses to protect an operator""s eyes when operating a shear tool in a manufacturing domain.
In private, a shear operator takes whatever precaution he or she deems sufficient during shearing operations. Many lacerations and occasionally more serious injuries such as inadvertent amputations have been documented as resulting from shearing operation accidents both in the metalworking industry and in the private sector.
Therefore, what is clearly needed is an improved shearing apparatus that enables an operator to keep his or her hands above and out of the way of the cutting surfaces of the shear or the sharp edge of the material being sheared. Such an improved apparatus would cause fewer injuries and would also provide for more freedom of direction in a shear path through the material being sheared.
In a preferred embodiment of the present invention a shearing tool is provided, comprising a fulcrum shaft, a first blade rigidly attached to the fulcrum shaft, a first element also rigidly attached to the fulcrum shaft and spaced apart on the shaft from the first blade, and a second blade contiguous with a second element, the second blade pivoted on the fulcrum shaft at one end of the blade, and between the attachment positions of the first blade and the first element such that relative rotation of the first and second elements causes relative rotation of the first and second blades producing a shearing action.
In some preferred embodiment the first element is a frame element of the shearing tool, and the second element is a link or handle contiguous with the second blade at a point on the blade side of the fulcrum, causing cut material to flow under operating elements and a user""s hand. Also in some preferred embodiments the second element is a contiguous link and handle arranged such that urging the handle toward the frame element provides the relative rotation producing a shearing action. In still further embodiments the first element is a frame element of the shearing tool, and the second element is a link or handle contiguous with the second blade at the one end of the blade pivoted to the fulcrum shaft. In yet other embodiments the second element is a part of a multi-link assembly for providing a mechanical advantage in rotating the second blade on the fulcrum shaft.
In some cases the first element comprises a first link contiguous with a first handle, the second element comprises a second link contiguous with a second handle, and the second link joins the second blade on the blade side of the fulcrum away from the one end pivoted at the fulcrum shaft. Also in some cases the second link joins the second blade at the one end pivoted at the fulcrum shaft.
In still other embodiments the second element comprises a second link contiguous with a second handle and the first element is a part of a multi-link assembly connected to a first handle for providing a mechanical advantage in rotating the second blade on the fulcrum shaft. In still further embodiments a powered unit provides the relative rotation between the first and the second blades.
In another aspect of the invention a method for shearing sheet material is provided, comprising the steps of (a) rigidly attaching a first blade to a fulcrum shaft; (b) rigidly attaching a first element to the fulcrum shaft, at a position on the shaft leaving a space between the first blade and the first element; (c) pivotally mounting a second blade having a contiguous second element to the fulcrum shaft at a first end of the blade and in the space between the first blade and the first element; and (d) rotating the second element relative to the first element, causing relative rotation between the first and the second blades to shear the sheet material.
In preferred embodiments the first element is a frame element of the shearing tool, and the second element is one of a link or handle contiguous with the second blade on the blade side of the fulcrum. Also in some preferred embodiments the second element is a contiguous link ending in a handle arranged such that urging the handle toward the frame element provides the relative rotation to shear the sheet material. In still further embodiments the first element is a frame element of the shearing tool, and the second element is a link or handle contiguous with the second blade at the first end of the blade pivoted to the fulcrum shaft.
In yet other embodiments of the invention the second element is a part of a multi-link assembly for providing a mechanical advantage in rotating the second blade on the fulcrum shaft. In still other embodiments the first element comprises a first link contiguous with a first handle, the second element comprises a second link contiguous with a second handle, and the second link joins the second blade on the blade side of the fulcrum.
In some cases the second link joins the second blade at the first end pivoted at the fulcrum shaft. In still other cases the second element comprises a second link contiguous with a second handle and the first element is a part of a multi-link assembly connected to a first handle for providing a mechanical advantage in rotating the second blade on the fulcrum shaft. In yet other cases there is a step for applying a powered unit to cause the relative rotation between the first and the second blades to shear the sheet material.
In embodiments of the invention described below in enabling detail, for the first time a shearing tool is provided that allows cutting of all sorts of sheet materials with substantially improved function and safety.